Researchers utilize gene therapy method to raise bigger pigs

WASHINGTON - Here come the super pigs. Medical researchers using gene therapy figured out a way to make young hogs grow 40 percent larger and faster.

Scientists said the technique, which stimulates production of the pigs' growth hormones, would be a boon for livestock farmers - and eventually could be used to treat children with growth problems and to prevent muscle deterioration in AIDS and cancer patients.

"We think that over the long term this is going to be a defining technology that will change the face of how agriculture is done," said the lead scientist, Robert J. Schwartz, a professor of molecular and cellular biology at Baylor College of Medicine in Houston.

The prospect of biotech hogs also is likely to raise new questions in a growing worldwide controversy over genetically engineered food. The United States already is locked in a trade war with the European Union over the EU's ban on beef from cattle injected with hormones.

"I don't think most consumers are very interested in eating hormone-treated meats," Rebecca Goldburg, senior scientist for the Environmental Defense Fund, said Tuesday.

Livestock and poultry have been getting bigger, leaner and faster-growing for years because of improvements in genetics, nutrition and housing, and the use of hormones in cattle.

But the results reported by Schwartz's team, which are published in the December issue of Nature Biotechnology, are especially dramatic. All the improvements made in hog production over the past two decades have pigs maturing only 10 percent faster than they used to.

The key to the new technology is a synthetic chemical that's inserted into a biodegradable piece of DNA, then injected into the leg of a 2-week-old pig. The chemical in turn causes the pig's pituitary gland to secrete higher than normal levels of growth hormone.

Two months after the injection, treated pigs weighed 92 pounds, compared with 65 pounds for an untreated hog. The treated pigs eat 25 percent less feed, which would amount to huge savings for the farmer, and they are ready for slaughter two weeks earlier, Schwartz said Tuesday. The price of feed accounts for half the cost of raising a hog.

The pigs also are expected to produce less manure, he said. Hog waste is a growing environmental concern in many states.

Additional research will have to be done to show the meat is safe for human consumption, and the treatment has no negative long-term impact on animals. The treatment would have to be approved by the Food and Drug Administration before it could be used commercially.

The technology could be used in humans as a less-expensive, more natural alternative to injecting AIDS patients with growth hormones, a treatment that costs as much as $20,000 a year, Schwartz said.

A drug could be administered to switch patients' hormone secretion off and on.

"This is extremely interesting work, but it has some problems with how the consumer will receive it," said Max Rothschild of Iowa State University, one of the nation's leading authorities on pig genetics.

"Will consumers eat animals that are treated in such a fashion? The jury is still out. . . . In Europe, the answer is absolutely not."

It would be far less controversial to continue improving pigs by identifying genes that control growth and other traits, he said.

Goldburg said it will take considerable more research to prove the technology is safe for pigs and humans.